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YFZ450Ridr
10-30-2006, 04:36 PM
im currently putting a new piston/rings setup in my yfz. im getting a wiseco piston but im not sure if i should stick with stock compression 11.5:1 or bump up to a 12:1. can i still run pump gas with a 12 and have it reliable? im leaning twards stock compression but wanted a second oppinion. thanks.
cals400ex
10-30-2006, 06:15 PM
12:1 should be fine on pump gas. i would go that route for sure.
2muchquad
10-30-2006, 09:22 PM
i run a wiseco 13.5 to 1 in my 426 with no problems on 93oct.
400eXr1d3rZ
10-30-2006, 09:45 PM
13:1 Would be fine on 93.
cals400ex
10-31-2006, 01:19 PM
Originally posted by 2muchquad
i run a wiseco 13.5 to 1 in my 426 with no problems on 93oct.


i don't know what kind of 426 you have but if it is an atv then that may be a little much for pump gas.
400exrider707
10-31-2006, 01:38 PM
Originally posted by cals400ex
i don't know what kind of 426 you have but if it is an atv then that may be a little much for pump gas.

Yeah especially for an air cooled motor like the EX. More than likely it could be because the wiseco pistons for the 400s are not the correct advertised compression ratios.
11-01-2006, 10:33 AM
13.5:1 comp running on 93 :huh :huh


you have to run race gas with anything over 12:1 on that big of a motor
11-01-2006, 10:43 AM
12:5.1 is about as high as you want to go on pump gas. Any higher compression on pump gas and your risking it.

13:5.1 you want race gas. Alot of people even run race gas in 12:5.1 comp.

My hybrids stock compression is 12:5.1 and i run pump gas. So 12:5.1 must be the limit cause i don't think yamaha would have made a motor that needs race gas stock.
Toadz400
11-01-2006, 12:51 PM
Originally posted by slow
12:5.1 is about as high as you want to go on pump gas. Any higher compression on pump gas and your risking it.

13:5.1 you want race gas. Alot of people even run race gas in 12:5.1 comp.

My hybrids stock compression is 12:5.1 and i run pump gas. So 12:5.1 must be the limit cause i don't think yamaha would have made a motor that needs race gas stock.

I know up to 13.5:1 on a dirtbike engine is safe on pump gas depending on the temperature and altitude, but 13:1 would probably be getting close to the limit on a 450 quad.

And why are you giving advice on engines slow? You can't even figure out what's wrong with your quad or even how to take anything apart.:ermm:
YFZ450Ridr
11-02-2006, 06:36 AM
alright thanks for the info guys, appreciate it.